Abstract
The fine particles produced during the desertification process provide a rich material source for sand and dust activities. Accurately locating the desertified areas is a prerequisite for human intervention in sand and dust activities. In arid and semi-arid regions, due to very sparse vegetation coverage, the microwave surface scattering model is very suitable for describing the variation of topsoil property during the process of desertification. However, the microwave backscattering coefficient (MBC) trend of the soil during the desertification process is still unclear now. Moreover, the MBC of a resolution unit usually involves the contribution of soil and vegetation. These problems seriously limit the application of microwave remote sensing technology in desertification identification. In this paper, we studied the soil MBC change trend during the desertification process and proposed a microwave backscattering contribution decomposition (MBCD) model to estimate the soil MBC of a resolution unit. Furthermore, a simple microwave backscattering threshold (SMSBT) model was established to describe the severity of desertification. The MBCD and SMSBT models were verified qualitatively through landscape photos of sampling points from a field survey in November 2018. The results showed that the MBC would gradually decline with the deepening degree of desertification. The MBCD model and the corresponding least squares method can be used to estimate the soil MBC accurately, and the SMSBT model can accurately distinguish different degrees of desertification. The results of desertification classification showed that more than 68% of the dry bottom of the Aral Sea is suffering from different degrees of desertification.
Highlights
IntroductionThe United Nations Convention to Combat Desertification (UNCCD) defined desertification as land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities [1,2,3,4,5,6,7,8]
The results showed that when there are only soil and vegetation in a resolution unit, the microwave backscattering contribution decomposition (MBCD) model and the corresponding least squares method can accurately estimate the backscattering coefficient of the soil and vegetation within the resolution unit
If the fraction of the scatterers within a resolution cell can be measured or estimated, the MBCD model can be extended to the backscattering contribution decomposition and backscattering coefficient estimation of multiple scatterers within a resolution unit
Summary
The United Nations Convention to Combat Desertification (UNCCD) defined desertification as land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities [1,2,3,4,5,6,7,8]. The desertification process produces many sand and dust particle grains, providing rich material for sand and dust activities [9]. The Aral Sea region, one of the world’s worst disaster areas, is suffering from a rapid process of desertification. The sand and dust particles aroused from the dry bottom of the Aral Sea are rich in salt and toxic substances, resulting in both the Remote Sens.
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